The late October calm of the Baltic Sea was rudely interrupted Thursday in what German broadaster Deutsche Welle describes as "an incident straining the fragile friendship between Germany and its eastern European neighbor."

Shots were fired off the holiday island of Usedom after the captain of the 670-passenger excursion vessel Adler Dania, owned by Adler Schiffe, declined to cooperate with customs officers and headed off to Germany instead of the nearest port as requested.

Polish authorities denied that shots were fired and insisted the coastguard simply used a flare pistol in order to prevent the captain leaving Polish waters.

Undercover Polish customs officials maintained they had found cartons of cigarettes as well as crates of liquor without Polish revenue stamps, says Deutsche Welle

When confronted, the captain refused any further searches and also refused to sail towards the next Polish port.

The customs officials maintain they alerted the coastguard, who allegedly fired shots. Undeterred, the captain steered a determined course back to Germany.

"The Polish authorities were prevented from doing their job," Deutsche Welle reports customs spokesman Janusz Wilczynski as saying "Then they were kidnapped by the German crew."

The background to all this is that Polish authorities are irked by German pleasure cruise operators who are said to sell Polish cigarettes and liquor at reduced prices and without proper customs clearance, supposedly "damaging Polish interests."

Adler Dania operates two separate bonded shops, one for German and the other for Polish territory. Germany had approved the German shop. At the time of the incident, the vessel was reportedly carrying 45 passengers.

Adler Schiffe has had earlier brushes with Polish authorities. In the most recent, 380,000 cigarettes--carrying Polish tax stamps--were confiscated in Swinoujscie earlier this month by non-uniformed individuals. They were removed in a private passenger car by non-uniformed personnel without any written explanation for the seizure being provided.

Adler Schiffe's version of this weeks incident is that the captain of the Adler Dania was informed that three non-uniformed persons were demanding entrance to a secure area of the ship. They were ordering the crew to collect the ship's liquor supplies, saying that it would be confiscated on the ship's arrival in Swinoujscie. The only identifications they showed were in Polish. They didn't have any form of international identification or any sort of search warrant.

According to Adler Schiffe, the captain treated the incident as provided for by the ISPS Code and immediately turned the ship around and headed for the nearest German port.

The Adler Dania was then pursued by what is described as a Polish border guard "speed" boat which apparently was unsuccessful in heading off the Adler-Dania--whose top speed is a thundering 13.6 knots.

Adler Dania immediately sent a message to the German Federal Border Police and made a complaint against the three intruders on the grounds of their illegal presence on board and unauthorized entrance to a restricted area.

Subsequently, the three were escorted to the Polish border.

Reportedly the Adler Dania is now docked and the Polish authorities say its presence in Polish waters is undesirable.